Negative Pressure?

17 years ago

Hi All

Recently replaced several old aluminium windows with triple pain low E argon filled windows. House is now pretty tight. It's a 1200 sq ft bungalow with finished basement. Gas oven now takes ages to heat up and initially gives off some fumes although they disappear almost immediately if door is opened (but I live in Saskatchewan and it's -30C outside!!). Also, ice forming around edges of storm doors and doors and sometimes they are hard to open (is air desperately trying to get in?) and main floor cold air returns making a high pitched whooshing sound. (I only have 2 air returns in entire house). I have put in a cold air intake (5" insulated pipe) that sits open between furnace and water heater in basement.(ending in a U shape) However, both furnace and water heater are vented directly to outside of house. Chimney is now also sealed up. Intake in basement is sucking in a lot of cold air but it hasn't helped the stove. So, I have a series of questions:

1) Do I have negative pressure issues?

2) Would more cold air returns help on the main floor?

3) Do I need a cold air intake directly into the furnace venting to deal with what may be infiltration issues?

Any advice greatly appreciated..what else should I look for re negative pressure?

As we are in a particularly cold spell my windows are frozen shut and I don't really want to open doors if I want to use my oven in a timely fashion. Gas range works fine.

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Comments (7)

czkidd
17 years ago
Try an ERV. This is a Energy Recovery Ventilator. Basically it works in either season by exchanging inside air with outside air. You can adjust it to make your home positive static in small increments. Talk to your local HVAC Contractor about these ERV's. They should help.
mr_havac
17 years ago
I sounds like you're exhausting an awful lot of air. Do you have several exhaust fans running? How about the furnace, is it forced draft and are you taking combustion air from within the house? Like czkidd recommends, maybe and ERV is the way to go but with the outside temps you folks have to deal with you may have to get one with a small strip heater to temper that incoming air a little better. I would do something pretty quick though, negative pressure in a house can be deadly if the house starts pulling air from flue pipes.
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pjb999
17 years ago
I agree that it could be dangerous - I suppose an easy test regarding the pressure is to put something smokey like a cigarette next to an outside door or window, and crack them slightly and see which way the smoke goes.

Somebody made the excellent point that a gas stove in a well-sealed house could be dangerous and they were wondering why/how the rules are so relaxed compared to furnaces and hw heaters....I would like to put a gas stove in when we remodel our kitchen, and it made me think. We dfinitely want a kitchen exhaust fan that goes outside instead of our useless recirculating one, but realise that exhaust fans, dryers etc can produce undesirable negative pressures too...

A whole-house erv would be nice to have, but the ones I've seen for sale are huge and I don't know where I'd fit one....but in books I've seen smaller ones that might fit near my furnace, and I could conceivably put the cold air intake parallel with the intake for the furnace/cold air return (I have a duct that draws cold air from outside which runs directly into the upper part of the cold air returns where they join together.
blacknumber1
17 years ago
Supply combustion air to the furnace and water heater and install a fresh air intake on your furnace, should solve the problems. If negative pressure still exists look at a HRV. Ideally a home should be at a slight positive pressure, but seldom is the case.
brickeyee
17 years ago
"Somebody made the excellent point that a gas stove in a well-sealed house could be dangerous and they were wondering why/how the rules are so relaxed compared to furnaces and hw heaters."

Stoves are not used nearly as much as house heat or a hot water heater, and all but the largest stoves are much smaller than either of these.
pjb999
17 years ago
That makes sense, I wondered if that was the reasoning....If we do go with a gas cooktop (don't like gas ovens as much) we will have a proper exhaust hood, anyway.

Just out of interest, is there a official method of testing for negative pressure?

And another thought, especially in colder climes like the original poster, should the cold air intake that runs into the furnace/furnace room be insulated? Mine isn't, unless it's some sort of double skin like the furnace/hw vents/chimneys...can't say I've seen frost or condensation on it, but wonder if that can be a problem, or is the idea that the ambient air preheats it a little?
mr_havac
17 years ago
pjb999, I believe this is yxegeordies post. If you have a question don't shanghai someone elses, start your own.